Abstract Cellulose is the most abundant form of biomass on earth, and is considered as an alternative for fuels and chemicals. The hydrolysis of cellulose to platform compounds, such as reducing sugars (RS), is one of the most important ways for the utilization of cellulose. In this study, the solid acid catalysts of SO42−-ZrO2/montmorillonite (SZ-Mt) were prepared by coupling SO42− with ZrO2 and then introducing into the interlayer of Mt using the coprecipitation method. Meanwhile, the catalytic performance of the SZ-Mt catalysts for the hydrolysis of cellulose to RS in water was studied. The catalysts were characterized by XRD, FT-IR, BET, SEM(EDS), NH3-TPD and XPS. The catalytic results showed that the SZ-Mt composite calcined at 500 °C with the molar ratio of S/Zr of 0.3 showed the highest total reducing sugars yield of 30.1%. The characterization results revealed that the surface S O bonds of sulfated zirconium oxide could gradually change from O=S-OH groups (type I, -HSO4) to O=S=O groups (type II, -S2O7). It was concluded that the surface S-OH groups in type I were responsible for the hydrolysis of cellulose in the low molar ratio of S/Zr and the new S-OH bonds formed by breaking the S-O-S bonds in type II were contributed to the conversion of cellulose in the high molar ratio of S/Zr. Finally, the mechanism of cellulose hydrolysis on the SZ composites was suggested.

中文翻译：

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在粘土基固体酸催化剂负载的纳米 SO42--ZrO2 上催化纤维素转化为还原糖

摘要 纤维素是地球上最丰富的生物质形式，被认为是燃料和化学品的替代品。纤维素水解为平台化合物，如还原糖（RS），是纤维素利用的最重要途径之一。在本研究中，SO42--ZrO2/蒙脱石固体酸催化剂（SZ-Mt）通过将SO42-与ZrO2偶联，然后使用共沉淀法引入到Mt的夹层中来制备。同时，研究了SZ-Mt催化剂对纤维素在水中水解为RS的催化性能。通过XRD、FT-IR、BET、SEM(EDS)、NH3-TPD和XPS对催化剂进行表征。催化结果表明，SZ-Mt 复合材料在 500 °C 下煅烧，S/Zr 摩尔比为 0.3，总还原糖产率最高，为 30.1%。表征结果表明，硫酸化氧化锆的表面 SO 键可以逐渐从 O=S-OH 基团（I 型，-HSO4）转变为 O=S=O 基团（II 型，-S2O7）。得出的结论是，在低 S/Zr 摩尔比下，I 型表面 S-OH 基团负责纤维素的水解，而 II 型中 SOS 键断裂形成的新 S-OH 键有助于转化S/Zr 的高摩尔比的纤维素。最后，提出了纤维素在 SZ 复合材料上水解的机理。得出的结论是，在低 S/Zr 摩尔比下，I 型表面 S-OH 基团负责纤维素的水解，而 II 型中 SOS 键断裂形成的新 S-OH 键有助于转化S/Zr 的高摩尔比的纤维素。最后，提出了纤维素在 SZ 复合材料上水解的机理。得出的结论是，在低 S/Zr 摩尔比下，I 型表面 S-OH 基团负责纤维素的水解，而 II 型中 SOS 键断裂形成的新 S-OH 键有助于转化S/Zr 的高摩尔比的纤维素。最后，提出了纤维素在 SZ 复合材料上水解的机理。